It's exciting: enter a road race and the tension mounts from the moment you get to the start. Give yourself a realistically challenging target time and the satisfaction and frustration at hitting or missing it can be enormously motivating.

It's brilliant stress-management: like a good night's sleep or a hot bath (but unlike booze or gluttony) it not only takes you away from your worries, but leaves you feeling better to deal with them on your return.

It can be euphoric: many runners will tell you about the pleasant, unexpected bonus of a "runner's high", and even an ordinary run leaves a feeling of satisfaction and well-being.

It's patches up your self-esteem: I never knew I had the discipline and commitment to maintain such a good habit. I may feel a bit of a fraud when people congratulate me on it - only I know how many times I haven't gone running when I knew I should have - but I still enjoy it.

It's constructively competitive: most of the time you're running against yourself, but on any club run - and especially in any race - there will be someone you'll feel you should be able to catch. And if he or she accepts the challenge you'll both run harder as a result.

It embodies a practical and positive philosophy: in a world where £17.2bn was spent on advertising in the UK in 2003, all with the implicit message that "you are what you buy", it's good to spend time in a more rewarding world where "you are what you do".

It's cheap: all you need to buy is a pair of shoes. The will to do something about your life, the vision to see how much better even a foul-weather run will leave you feeling than the same length of time slumped in front of a TV, and the determination to keep running even when your lungs are rasping and your legs moaning are each a bit like true love - they can only be given not bought, and they will enrich your life forever. Are you generous enough to give yourself one pair of shoes, a little will, a glimpse of vision and a pinch of determination?

It may lengthen your life: according to a recent study "The performance of the heart declines steadily as men get older. The hearts of our inactive older volunteers showed a 20% fall in their pumping performance compared to the 20 year-olds, but the veteran athletes have the cardiac performance that is the same if not greater than the inactive 20-year-olds."